The Purkinje Effect in Luminance Measurements of Air Force Phosphorus
AERONAUTICAL SYSTEMS DIV WRIGHT-PATTERSON AFB OH MATERIALS LAB
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A formula is derived for relating effective and photopic units of luminance by means of Weavers interpolated data J. Opt. Soc. Amer. 39281, 1949 for the mesopic luminosity functions. The formula is applied to the spectra of 4 typical AF luminescent phosphors results are compared with experimental data. Individual values of BB reveal considerable dispersion around the mean value, particularly as the match becomes more heterochromatic B is the specified luminance measured in effective units of luminance, and B is the luminance of the same area in photopic lamberts. Averaged values agree with the BB curves. Weavers data is tentatively accepted for conversion between effective and photopic units in luminance measurements of luminescent materials. A study of the effect of color on the results of the Purkinje effect showed that colors furthest removed from that of the standard 2360 deg K source exhibited the most pronounced change in BB with decreasing luminance. The blue phosphor produced over 4 times as much visual response per unit energy at the lowest luminances than at luminances above 1 ft-lambert the red phosphor produced about 15 the amount.
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